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Updated: 2017 May 19, 18:44 UT
Event Rank : 99
(The event Rank is a measure of the likelihood of observing an event, and is equal to the probability of at least one successful observation by a team of two observers spaced 1/8 path width just inside opposite sides of the predicted path. An event rank of 100 indicates that the prediction is expected to be very accurate).
THE UPDATED PATH
Note: The duration given in the line below is the interval during which the occultation shadow sweeps across the Earth - please see the minute markers on the map to determine the approximate time for your location.
On 2017 Jul 09 UT, the 75 km diameter asteroid (25) Phocaea will occult a 11.9 mag star in the constellation Vulpecula for observers along a path across eastern Queensland, and north-eastern New South Wales, passing over Port Macquarie, Townsville, Innisfail, Cairns and Cooktown.
In the case of an occultation, the combined light of the asteroid and the star will drop by only 0.22 mag to 10.30 mag (the magnitude of the asteroid) for at most 12.9 seconds. This event will only be observable electronically.
This update is based on UNSO/Flagstaff astrometry for the asteroid kindly provided by Hugh Harris, astrometry for the asteroid kindly provided by Bill Owen, astrometry for the asteroid kindly provided by the IAU Minor Planet Center. This work has made use of data from the European Space Agency (ESA) mission Gaia (http://www.cosmos.esa.int/gaia), processed by the Gaia Data Processing and Analysis Consortium (DPAC, http://www.cosmos.esa.int/web/gaia/dpac/consortium). Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement.
Additional details of this and other events are available at Steve Preston's website at http://www.asteroidoccultation.com/
EVENT DETAILS SUMMARY :Important Note regarding Accuracy:
The uncertainty interval in path widths given above (and shown as a 1-sigma uncertainty ellipse on the plot) refers to RMS deviation and is applied as a +/- range. In other words, a path uncertainty of 1.0 path widths means that the actual center of the asteroid's shadow path should fall within plus or minus 1 path width of the plotted path center. However path errors larger than 1 sigma have been observed so observers should be alert for primary occultations within plus or minus 3 sigma of the updated path.
Further, almost all asteroidal satellites discovered so far have been found within 10 diameters of the asteroid (since this distance is deep enough within the gravitational well to be stable over long timescales). Therefore, if monitoring for secondary events, observing out to about 10 path-widths either side of the predicted track remains worthwhile.
We therefore recommend that you monitor for events if your observing location is up to +/- 10 path-widths from the predicted track. If not monitoring for occultations by secondary bodies you should observe from locations within 3 sigma of the nominal path.
In terms of time, the predictions are now usually accurate to about +/- 0.3 minute so you should be most attentive during the predicted minute of the event. However if intending to catch a potential satellite occultation you should start observing at least 10 times the predicted central duration before the predicted closest approach time for your location, and continue for a similar period afterwards.
Occultation of UCAC4-581-112458 by 25 Phocaea on 2017 Jul 9
Centre Star Star Sun Path Limits Error Limits Alt
E. Longitude Latitude U.T. Alt Az Alt Limit 1 Limit 2 Limit 3 Limit 4 Crn
o ' " o ' " h m s o o o o ' " o ' " o ' " o ' "
Longitude Longitude Longitude Longitude
155 22 48 -35 0 0 16 58 22 24 334 -46 155 50 35 154 55 3 156 6 11 154 39 32 0.06
154 45 45 -34 0 0 16 58 31 25 335 -46 155 13 9 154 18 23 155 28 32 154 3 5 0.06
154 9 30 -33 0 0 16 58 40 27 335 -47 154 36 32 153 42 30 154 51 42 153 27 23 0.06
153 33 59 -32 0 0 16 58 50 28 335 -47 154 0 41 153 7 19 154 15 39 152 52 24 0.06
152 59 9 -31 0 0 16 59 0 29 336 -48 153 25 31 152 32 49 153 40 18 152 18 5 0.06
152 24 57 -30 0 0 16 59 10 30 336 -48 152 51 1 151 58 55 153 5 38 151 44 22 0.06
151 51 21 -29 0 0 16 59 20 31 336 -49 152 17 7 151 25 36 152 31 34 151 11 12 0.06
151 18 18 -28 0 0 16 59 31 32 337 -49 151 43 48 150 52 50 151 58 5 150 38 35 0.06
150 45 45 -27 0 0 16 59 42 33 337 -50 151 11 0 150 20 33 151 25 9 150 6 26 0.06
150 13 42 -26 0 0 16 59 54 34 337 -50 150 38 41 149 48 44 150 52 42 149 34 45 0.06
149 42 4 -25 0 0 17 0 6 35 337 -50 150 6 50 149 17 20 150 20 43 149 3 29 0.06
149 10 52 -24 0 0 17 0 18 36 337 -51 149 35 24 148 46 20 149 49 10 148 32 37 0.06
148 40 2 -23 0 0 17 0 30 37 338 -51 149 4 22 148 15 42 149 18 0 148 2 6 0.06
148 9 33 -22 0 0 17 0 43 39 338 -51 148 33 42 147 45 25 148 47 14 147 31 54 0.06
147 39 23 -21 0 0 17 0 56 40 338 -51 148 3 21 147 15 26 148 16 47 147 2 2 0.06
147 9 32 -20 0 0 17 1 9 41 338 -52 147 33 20 146 45 45 147 46 40 146 32 26 0.06
146 39 57 -19 0 0 17 1 22 42 338 -52 147 3 35 146 16 19 147 16 50 146 3 5 0.06
146 10 36 -18 0 0 17 1 36 43 338 -52 146 34 6 145 47 8 146 47 16 145 33 59 0.06
145 41 30 -17 0 0 17 1 50 44 339 -52 146 4 52 145 18 10 146 17 57 145 5 5 0.06
145 12 36 -16 0 0 17 2 5 45 339 -52 145 35 50 144 49 23 145 48 51 144 36 24 0.06
144 43 54 -15 0 0 17 2 19 46 339 -52 145 7 1 144 20 48 145 19 57 144 7 52 0.06
144 15 22 -14 0 0 17 2 34 47 339 -52 144 38 22 143 52 22 144 51 15 143 39 30 0.06
143 46 59 -13 0 0 17 2 49 48 339 -53 144 9 53 143 24 5 144 22 42 143 11 16 0.06
143 18 43 -12 0 0 17 3 4 49 339 -53 143 41 32 142 55 55 143 54 18 142 43 9 0.06
142 50 35 -11 0 0 17 3 20 50 339 -53 143 13 19 142 27 52 143 26 2 142 15 9 0.06
142 22 33 -10 0 0 17 3 36 51 339 -53 142 45 12 141 59 54 142 57 53 141 47 13 0.06
Uncertainty in time = +/- 4 secs
Prediction of 2017 May 19.0
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